1. Field of the Invention
The present invention concerns a method and device for dynamically treading fruit or even vegetables.
In particular, the invention is advantageously applicable to the bursting of grapes, beginning right with the crop of de-stemmed grapes or in whole bunches, for the elaboration of white, rosé or red wines.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
In a vinification process at the end of which the grapes is transformed into wine, treading is the operation which consists of pressing or crushing the grapes to burst them open and to release their components in order to obtain a grape must which is in contact with the skins.
The invention is also applicable to the bursting of apples for cider production or of other fruit or even vegetables, for use in an ulterior process of producing juices or concentrates of these.
The objective is to achieve, through the present innovation, the bursting of fruit or even of certain vegetables, in order to increase exchanges between the liquid and solid phases within the whole grape must obtained in this manner which will be reused later, for instance in a maceration process.
With respect to vinification, the treading method and machine according to the invention consist of bursting the grape berries to obtain a grape must then intended for maceration, without crushing neither the pips nor the possibly present grape stalks or other plant debris (leaves, stems, . . . ), the crushing of which could release and diffuse substances undesirable for good vinification (release of oils or polyphenolic compounds in uncontrolled quantities).
Especially on the oenological level, what is sought is the largest contact area possible between the juice and the skin of the grapes, during the maceration process.
Crushing the grape berries will have these effects:                establishing contact with the grape must, of the yeast present on the outside surface of the skin of the berries, in the case of spontaneous vinification;        good maceration or exchange by dissolution of polyphenols (coloring matter, tannins, . . . ) residing primarily on the inner surface of the grape skin, during red wine production;        reducing the risk of having residual reducing sugars at the end of alcoholic fermentation.        
This process of obtaining fermentative must from grapes can also be applied to other fruit containing seeds or pits, or even to vegetables.
In order to obtain a quality grape must and to extract, during the maceration phase, the maximum of polyphenolic compounds, it is necessary that the following conditions be met:                all berries without exception grape must be crushed;        the grape berries must not only be crushed to release the juice and seeds, but the skin grape must also be completely spread out so as to present the largest exchange surfaces possible for both its sides, inside and outside;        if the skin folds over itself after bursting, the grape juice must be able to infiltrate and circulate freely over the entire surface of the inside and outside of the skin It is in effect necessary to extract from the skin surface all compounds that are indispensable to vinification such as yeast and polyphenols (coloring matter, tannins, . . . );        under no circumstances must the pips or pieces of stalks or vegetable debris be crushed or their integrity is impaired in order to avoid the release of substances that are undesirable for the quality of the grape must.        
Mechanical wine-presses have been available commercially for many years. They have superseded the age-old operation of treading by hand or foot which consisted of crushing, between the fingers or with the feet, the grape bunches brought in by manual harvest. For the most part they are being built, based on the principle of crushing berries between two more or less notched rolls rotating in opposite directions to each other. The differences between the solutions proposed by the manufacturers have to do with the geometry of the rolls or their notching, but the principle remains basically the same.
The rolls are made of food materials (rubber, polyurethane) and particularly not of hard materials (steel, stainless steel for example) to limit the effects of crushing seeds, plant or other organic debris.
Most of these systems allow adjusting the distance between the rolls, to increase or reduce the crushing of the grape berries, but also to adapt to the size of the grapes (which varies for different vine-stocks) or to the flow of fruit to be processed.
In consideration of their principle of mechanical crushing of the berries (rolling mill system, calendering), these wine-presses do indeed let these berries be crushed in order to release the juice, pulp and seeds But their major disadvantage remains that the berry opens only over a small surface, sufficient to evacuate its content through the wine-press. In effect, by passing through the wine-press the berry is progressively crushed. The pressure thereby generated inside the fruit makes the skin split open, generally where it is attached to the pedicel. After the exit of the grape components and the passage through the wine-press, the grape skin collapses on itself and, during the maceration process, limits the exchange surface between the juice and the inside wall of the berry skin This fact induces a longer maceration process (in order to extract as much as possible of the active components located at the inside of the skin turned back on itself), and of less quality in oenological terms.
Considering the design of these wine-presses, a fixed distance separates the two rolls of the wine-press during the treading. This distance may or may not be adjustable to adapt it to the average size of the berries and the intensity of the desired treading. So it is this distance which defines the minimum size of the grape that will be pressed between the rolls. Grapes and objects of smaller size than the distance between the rolls can therefore pass undamaged, while all other objects are being systematically pressed between the rolls.
Now, in a grape harvest, the size of the grapes is not constant, but depends on the vine-plant, and also on the degree of ripeness of the grapes. Thus, there will always be a not insignificant proportion of grapes with a diameter smaller than the distance between the two rolls, grapes which will therefore not be crushed and which will be unable to participate efficiently in the maceration process. Therefore, if one wants to subject almost all grapes to treading, one is obliged to reduce the distance between the rolls, at the cost of having to risk crushing or breaking down, in their entirety, seeds or plant material such as grape stalks.
In this case, the disadvantage of this type of equipment is that the output is linked to the distance between the rolls, for a given roll length. A significant increase of this output can therefore lead to degrading the treading quality.
On the other hand, one knows, for example in the elaboration of fruit juices, how to achieve the separation of liquid and solid matters of fruit, using centrifugation methods and machines.
However, for the application of these methods and machines, it is indispensable to first perform a grinding operation of all parts of the fruit, consequently including fruit pits or seeds, so as to then be able to extract the liquid parts of the grape must resulting from this grinding operation, by centrifugation, through a filter rotating at high speed.
In the FR-1.595.035 document a grape treader is described. According to this document, crushing of the berries is achieved by using a rotary beater with radial blades, so that this crushing operation is obtained through the beating action exerted directly on the berries by said blades. The rotary beater is not used to impart any kinetic energy to the berries but to make them burst through successive strokes by these blades, along a tunnel. There is no effect of centrifugal acceleration in a single level of fruit.
In the U.S. Pat. No. 4,957,043 document, a fruit disintegration device is described which includes a chamber with an inlet opening and an outfeed canal, this chamber containing a drive rotor to accelerate the speed of the fruit around a circular trajectory and then to discharge the fruit through said tangential outfeed channel into a separation chamber where the fruit is crushed on a fixed wall away from the rotor.
According to this document, the fruit is poured into a chamber in which a vertical rotor consisting of a part with a U profile is mounted so that it rotates around a horizontal axis. The fruit dumped by an infeed device is introduced between the longitudinal blades of this U-shaped rotor, and, under the effect of centrifugal force the fruit is ejected one by one into a channel leading to a separation chamber in which a fixed wall is installed facing the exit of the channel and against which the fruit propelled by kinetic energy is crushed. It would seem that a single fruit is ejected into the connecting channel whenever one of the open ends of the rotor appears opposite the entrance of said channel
Such a device cannot be contemplated, nor is it applicable, on a practical level, to the treading of small fruit such as grapes or other berries, if one considers that the passage of the latter, one by one, from the chamber of acquisition of kinetic energy towards the separation chamber over a connecting channel would require an excessively long time, which is completely incompatible with the treading of grapes coming in from the harvest. On the other hand, a portion of the kinetic energy imparted by the rotor is dissipated during the passage of the fruit through the connecting channel The performance of this device would be clearly insufficient for applying it to grape treading. Finally, the fruit finds itself projected at a right angle to the fixed crushing plane, since such a process does not permit a development of the fruit skin which is indispensable for maceration in the wine-making process. This orthogonal projection of the grapes leads in fact to grapes crushing on themselves to release their components with, as a result, an effect that is identical to that obtained by traditional treading by means of machines with rollers, which is to say the folding of the grape skin on itself instead of being developed in the grape must.
As previously indicated, the invention is essentially and advantageously usable for achieving the separation of the liquid and solid phases of juicy fruit, in particular of fruit in the form of berries, such as grapes. However, we do not exclude the application of the invention to treading of certain vegetables, by means of adaptations of the treaders, depending on the nature of the vegetables to be processed. Under these conditions, the word “fruit”, or even the word “berry” should be considered as equivalent to the term “vegetable” in the description which follows and in the claims.
The aim of the present invention is precisely to remedy the aforementioned disadvantages of treading devices with rollers and its goal is to make available to professionals interested in the utilization of this type of equipment, a dynamic wine-press allowing complete crushing of the fruit, berries or vegetables passing through it, and to release their liquid and solid matter, in order to constitute a high-quality grape must, as a preamble to ulterior operations of maceration or fermentation.